In integrated circuit (IC) design, many applications exist for high-performance, on-chip capacitors. These applications include dynamic random access memories (DRAM), voltage controlled oscillators, phase-locked loops, operational amplifiers, and switching capacitors. Such on-chip capacitors can also be used to decouple digital and analog integrated circuits from the noise of the rest of the electrical system.
Capacitor structures for ICs have evolved from the initial parallel plate capacitor structures comprised of two conductive layers separated by a dielectric to different capacitor designs to meet specifications for high capacitance in increasingly smaller devices. These designs may include trench capacitors, metal-oxide-metal (MOM) capacitor designs and interdigitated finger MOM capacitor structures, for example. For example, in a DRAM device, the capacitors can be deep trench capacitors disposed inside a semiconductor substrate, or stack capacitors stacked on a semiconductor substrate.